Safety device for self-propelled projectiles



Nov. 9, 1954 E. w. BRANDT SAFETY DEVICE FOR SELFPROPELLED PROJECTILESFiled Oct. 10, 1950 BY%IMI/ ATTORNEYS. v

United States Patent SAFETY DEVICE FOR SELF-PROPELLED PROJECTILES EdgarWilliam Brandt, Geneva, Switzerland, assignor to Anstalt fur dieEntwicklung Von Erfindungen und gewerblichen Anwendungen Energa, Vaduz(Liechtenstein), a corporation of Liechtenstein Application October 10,1950, Serial No. 189,434

9 Claims. (Cl. 102-49) This invention relates to a safety device forselfpropelled or rocket projectiles.

Projectiles functioning by reaction generally comprise a charge ofpropellent powder in a combustion chamber provided with nozzles, throughwhich the gases of combustion are expelled, to impart an increasedvelocity to the projectile.

Since the nature of the combustion of the powder is governed mainly bythe pressure and temperature, to which the interior of the combustionchamber is raised, various means have been proposed for influencing andregulating these physical factors.

However, the choice of a given quantity of propellent powder for apredetermined volume and discharge of the nozzles is not sufiicient tomaintain the current combustion conditions of the powder. Combustionalso depends upon the state of the batch of powder, its degree ofdryness and atmospheric conditions (surrounding temperature, humidity,and so forth).

It is therefore necessary to endeavor to prevent as much as possible,the disadvantages which may arise from these variations, namelyinaccuracyof shooting and the risk of explosion of the combustionchamber in the event of sudden excess pressure.

Various means have already been proposed for increasing the discharge ofthe nozzles, for example valve devices, but the latter are liable to berendered inoperative by the very high pressures and temperatures towhich they are subjected. Furthermore, when valves are used as safetydevices, the additional propulsion effect of the discharge of the gasesthrough convergent-divergent nozzles is not availed of.

The present. invention aims at obviating the foregoing disadvantages andcontemplates a safety device for the type of rocket projectile having aplurality of convergentdivergent nozzles at the end of the combustionchamber of the rocket projectile.

According to the present invention, at least one of the aforesaidnozzles, and preferably a centrally disposed one, is closed by an anvilor closure member, which also serves as a percussion cap carrier for afiring cap placed in contact with the igniting charge of theself-propulsion material. This anvil is held in place by a retainingmember or element adapted to shear under the effect of a pressuregreater than a normal operating pressure within the combustion chamber,but less than the pressure at which physical disruption of the chamberparts occurs, that is, this retaining member yields under the effect ofa pressure greater than the pressure usually generated within thechamber and tolerated as a usual operating condition, whereby the anvilor closure member is freed to be ejected by the self-propulsion gaseswhich are thereafter discharged through this additional nozzle.

In other words, if under normal conditions of temperature and pressure,the propulsion of the projectile is assured by a number of nozzles N,N+I nozzles are, however, available in case of predetermined excessivepressure.

The closure member or anvil, acting as a valve, comprises in additionthe cap for igniting the charge on percussion and is disposed in theinterior of a central nozzle. Consequently when the anvil is ejectedunder the effect of an excessive pressure, the symmetry of the nozzlesis not modified and the trajectory of the projectile is consequently notaffected.

Furthermore, upon the functioning of the safety device, the cap-carryinganvil ejected rearwardly does not -1 face'of the nozzle 13 and in.addition is retained by angive rise to any danger, because the ejectedpart (anvil, cap and so forth) has a low mass and negligible inertiarelatively to the thrust of the gases acting thereupon.

In order to provide a readily detachable unit, the ignition charge ispreferably contained in a case fitted on the external face of thecentral nozzle hereinbefore referred to.

According to another feature of the present invention, the novel deviceincludes an elastic element interposed between the anvil and the nozzle,thus providing a seal for the gases as long as the shear element has notyielded under the effect of the pressure.

Another embodiment of the invention comprises at the rear, in additionto an ignition cap, a firing pin sliding in a recess provided for thepurpose and struck by the hammer of the weapon on firing.

Moreover when the anvil. closes the central nozzle, the anvil or closuremember rests, in accordance with the invention, on an annular supportprovided by an abutment shoulder in the interior of said nozzle suchthat the shear element is protected from external pres-- sures andaccidental shocks, and only a suflicient thrust acting from the interiorof the combustion chamber will shear said element.

Other feaures of the invention will appear from the followingdescription taken in conjunction with the accompanying drawings whichillustrate diagrammatically and by way of example thc preferredembodiments thereof, and in which:

Fig. I is a longitudinal sectional view of the rear of a self-propelledprojectile equipped with the invention and taken on line 1--1 of Fig. 2'

Fig. 2 is a rear end view of the device shown in Fig. 1;

Fig. 3 is an enlarged sectional view taken on the longitudinal axis 3-3in Fig. 1 and showing the device provided at the end With an ignitingcharge;

Fig. 4 is a fragmentary enlarged axial section, showing the1 operationaldetail of the device with the cap' expelled; an

Fig. 5 is an axial section of a second embodiment of the invention.

The rear end of the combustion chamber 1 (Fig. 1), on the periphery ofwhich stabilising fins 2 are provided, acts as support for the deviceaccording to the invention, which comprises a nozzle support 3 closingthe rear end of the combustion chamber having the annularly disposednozzles 4 which are closed at their rear ends by closure plates 5. Saidplates are each held between an abutment provided on the inner face ofthe nozzle' 4- and la collar 6 of said latter made of heat-resistantmateria A device 7 is screwed into a central duct or passage 8 of thenozzle support 3, and the casing 9, containing the igniting charge,forms an extension of said device. The propellent is shown in the formof solid rods 10 (for example a nitrocellulose andnitroglycerinepowder), each resting with its end on the apex of a grid11,. the orifices of which are laterally oriented, soas to preventprojection of unburnt particles of powder through the nozzles 4.

Fig. 3 shows the constructional detail of the device 7, which comprisesa screw-threaded annular part or collar 12, containing a nozzle 13closed by a closure member or anvil 14 containing a cap 15, the latterbeing held in place by the fianging of the external edge of said anvil.The latter bears internally against an abutment 16 of the nozzle 13, anda washer 17 in contact with a shoulder 18 of the anvil 14 prevents theanvil or closure member from leaving its recess. A gas-tight plasticelastic packing element 19 (leather, wadding or the like) completes thegas-tight sealing of. device 7. Finally, the striker-carrying hammer ofthe weapon is partly shown at 28 opposite the cap 15.

According to a modified embodiment of the invention shown in Fig. 5, theanvil 14 includes, at its rear, in place of the cap 15, a small firingpin 20 adapted to slide in a bore 21 arranged opposite a percussion cap22 in front of said bore. In this embodiment, the rear opening of theanvil is closed by a plate 23. The casing 9 containing the ignitingcharge 24, is set on the external external ring 25. Finally andpreferably, the igniting charge in addition includes a relay charge 24a(Flg. 3) of aluminothermic material e. g. Thermite having a highcombustion temperature facilitating the ignition of the propellant 10,the'flame of thesaid material passing through perforations 26 providedon the periphery of the casing 9 which in turn is covered with a thinsheath 27.

The hereinbefore described device'operates as follows:

Before firing, the annularly disposed nozzles 4 are closed by the plates5, and the hereinbefore described device hermetically seals the centralduct 8.

When the firer presses the trigger of the weapon, the hammer 28 strikesthe cap 15 (Fig. 3) or the plate 23 (Fig. 5) in contact with the collarequipped firing pin 20. The defiagration of the percussion cap istransmitted to the igniting charge 24, 24a and the jet of, flameperforates the sheath 27 in passing through the openings 26 provided forthis purpose. Ignition is finally transmitted to the propelling agentrepresented by the rods symmetrically arranged around the ignitingcharge 24.

The gases of the self-propulsion combustion chamber attain a highpressure and temperature and in doing so shear the plates 5; the nozzles4 begin to discharge simultaneously and the projectile commences itstrajectory under the aciton of the initial velocity which it acquires.

If for any reason a predetermined pressure exceeds the limit toleratedby the strength of the combustion chamber walls, the regulating devicethen functions and, in accordance with the invention, the anvil 14carrying the firing pin is ejected after shearing of the washer 17 (Fig.4).

Thereafter, an additional nozzle 13 is available for the discharge ofgases from the combustion chamber 1 through the grid 11 and the centralduct 8. The pressure in the combustion chamber thereupon dropsinstantaneously below the danger limit.

The invention thus affords the advantage of permitting a greaterefficiency of auto-propulsion, since there is no longer any fear ofloading the container to the maximum.

Moreover the weight of the projectile is substantially reduced, sincethe wall of the container may be constructed of lesser thickness.

It is obvious that the invention has been described by way of exampleonly and that numerous modifications may be made in it without departingfrom the scope thereof as defined by the appended claims.

What I claim is:

1. In a rocket projectile having a combustion chamber,

closure means at the rear end thereof and having a plurality of maindischarge passages and a central passage all in communication with thechamber during flight of the projectile, a safety device comprising anozzle in said central passage, an elongated casing connected to theinner end of said safety nozzle and thereby supported in said centralpassage, an igniter charge in said casing, a closure member obturatingthe said nozzle, a primer cap carried by said closure member and indirect contact with the igniter charge, a retaining member, and anannular member holding said retaining member in position against saidsafety nozzle, said retaining member being constructed and arranged toresist normal operating pressure in said chamber and safety nozzle andto shear under the effect of an excessive pressure therein higher than apredetermined normal pressure whereby the closure member is released andexpelled.

2. In combination: a rocket projectile having a combustion chamber, andclosure means at the rear end thereof having a plurality of maindischarge passages and a central passage in communication with saidcombustion chamber; a nozzle in said central passage, a collar adaptedto engage the rear end of said closure means and having an interiortransverse shoulder therein; the said nozzle having aconvergent-divergent form with an enlargement in the divergent portionthereof to provide a shoulder; a closure member having a peripheralflange, the front shoulder of which flange is adapted to contact thesaid shoulder of said nozzle and the outer peripheral surface of whichflange is adapted to con-- tact the inner surface of said nozzle; and awasher engaging on one of its sides the shoulder of said collar andengaging on the other of its sides the rear end of said nozzle and therear shoulder of said flange; said washer being constructed and arrangedto resist pressurewithin the said nozzle up to' a predetermined amountand to shear under the effect of a pressure above the said predeterminedamount whereby said closure member is released and expelled from saidnozzle. 7

3. In combination: a rocket projectile having a combustion chamber, andclosure means at the rear end thereof having a plurality of maindischarge passages and a central passage in communicotion with saidcombustion chamber; a nozzle in said central passage, a collar adaptedto engage the rear end of said closure means and having an interiortransverse shoulder therein; the said nozzle having aconvergent-divergent form with an enlargement in the divergent portionthereof to provide a shoulder; a closure member having a peripheralflange, the front shoulder of which flange is adapted to contact thesaid shoulder of said nozzle and the outer peripheral surface of whichflange is adapted to contact the inner surface of said nozzle; anelastic packing ele ment in said enlarged portion in compressed contactbetween said nozzle and said closure member, and a washer engaging onone of its sides the shoulder of said collar and engaging on the otherof its sides the rear end of said nozzle and the rear shoulder of saidflange; said washer being constructed and arranged to resist pressurewithin the said nozzle up to a predetermined amount and to shear underthe effect af a pressure above the said predetermined amount wherebysaid closure member is released and expelled from said nozzle.

4. In combination: a rocket projectile having a combustion chamber and asupport having a plurality of discharge passages in communication withsaid combustion chamber, one of which passages is in the central axis ofsaid projectile and has a nozzle having a convergentdivergent form; acollar adapted to engage the rear end of said support and adapted tocontact the outer surface of said nozzle and having an interiortransverse shoulder therein; the said nozzle having an enlargement inthe divergent portion thereof to provide an internal shoulder; anelongated perforated casing connected to and opening into the convergentend of said nozzle and extend normal operating pressure in said chamberand to shear under the effect of a pressure therein higher than saidpredetermined pressure whereby the said closure mem ber is released andexpelled from said nozzle.

5. In combination: a rocket projectile having a combustion chamber and asupport having a plurality of dis charge passages in communication withsaid combustion chamber, one of which passages is in the central axis ofsaid projectile and has a nozzle having a convergentdivergent form; acollar adapted to engage the rear end of said support and adapted tocontact the outer surface of said nozzle and having an interiortransverse shoulder therein; the said nozzle having an enlargement inthe divergent portion thereof to provide an internal shoulder; anelongated perforated casing connected to and opening into the convergentend of said nozzle and extending into said combustion chamber; anigniting charge in said casing and said nozzle; a closure member havinga peripheral flange adapted to contact the said shoulder of said nozzleand the inner surface of said nozzle; a firing pin and a primer cap in acentral passage in said closure member and in contact with said ignitingcharge, the firing pin closing the area of the central passage; and aretaining member engaging the said'shoulder of said collar and the rearend of said nozzle and the said flange; the said retaining member beingconstructed and arranged to resist a predetermined normal operatingpressure in said chamber and to shear under the effect of a pressuretherein higher than said chamber; an elongated-perforated casing in saidpassage and extending into said combustion chamber, an igniting chargein said casing and said nozzle; and a charge firing and safety device insaid nozzle comprising a closure member obturating the divergent end ofsaid nozzle, gas-tight packing means between said nozzle and saidclosure member, means for preventing said closure member moving forwardin said nozzle, and a firing cap axially located in said closure memberand in contact with said igniting charge and exposed at the rear of saiddevice, safety releasing means for preventing said closure member movingrearward out of said nozzle, said safety releasing means including anelement in normally supporting relation to said closure member and beingsubject to shear and breakage under the effect of a pressure in saidnozzle higher than a predetermined pressure whereby the said closuremember is released and expelled from said nozzle.

7. In combination: a rocket projectile having a combustion chamber and asupport having a plurality of main discharge passages and a centrallydisposed passage terminating at its rear end in a convergent-divergentnozzle, said passages being in communication with said chamber; anelongated perforated casing in said passage and extending into saidcombustion chamber, an igniting charge in said casing and said nozzle;and a charge firing and safety device in said nozzle comprising aclosure member obturating the divergent end of said nozzle, gas-tightpacking means between said nozzle and sald closure member, means forpreventing said closure member moving forward in said nozzle, a firingcap axially located in said closure member and in contact with saidigniting charge, a firing pin in said closure member coaxial with saidcap, and a closing plate in the exposed end of said device juxtaposed tothe rear end of said firing pin, safety releasing means for preventingsaid closure member moving rearward out of said nozzle, said safetyreleasing means including an element in normally supporting relation tosaid closure member and being subject to shear and breakage under theeffect of a pressure in said nozzle higher than a predetermined pressurewhereby the said closure member is released and expelled from saidnozzle.

8. In a rocket projectile having a combustion chamber, closure means atthe rear end thereof and having a pluralin communication with thechamber during flight of the projectile, a safety device comprising anozzle in said central passage, a closure member obturating the saidnozzle and having a central bore and an external shoulder, an annularretaining element engaged against said shoulder, an annular memberholding said retaining element in position against said safety nozzleand shoulder, and a primer cap carried by the closure member in saidbore and closing the same, said retaining element being constructed andarranged to resist normal operating pressure in said chamber and safetynozzle and to shear under the eifect of an excessive pressure thereinhigher than a predetermined normal pressure whereby the closure memberis released and expelled.

9. In combination: a rocket projectile having a combustion chamber and asupport having a plurality of main -d1scharge passages and a centrallydisposed passage, a convergent-divergent nozzle terminating the rear endof the central passage, said passages being in communication with saidchamber, and a safety device in said nozzle comprising a closure memberobturating the divergent end of said nozzle and having a central boreand an external shoulder therein, a primer cap carried by the closuremember in said bore and closing the same, means for preventing saidclosure member moving forward in said nozzle, and safety releasing meansfor preventing said closure member moving rearward out of said nozzle,said safety releasing means including an annular element in normallysupporting relation to said closure member and engaged with the nozzleand subject to shear and breakage under the effect of a pressure in saidnozzle higher than a predetermined pressure, whereby the said closuremember is released and expelled from said nozzle, and means for holdingsaid annular element against said closure member and nozzle.

8. References Cited in the file of this patent UNITED STATES PATENTSNumber Name Date 2,400,242 Malina et al May 14, 1946 2,412,173 Pope Dec.3, 1946 2,457,839 Skinner Jan. 4, 1949 FOREIGN PATENTS Number CountryDate 14,000 Great Britain of 1896

